1. Field of the Invention
The present invention relates to orthopedic devices for protecting the human knee, and it relates more particularly to an orthopedic device adapted to protect the knee against injury from lateral forces and impacts which may occur during sports activities.
2. Description of the Prior Art
There is widespread need for knee protection apparatus capable of absorbing forces or impacts directed toward the lateral side of the knee and redistributing such forces or impacts along the leg so as to protect a previously injured knee from further injury. A typical circumstance where such knee protection equipment would be desirable is during a game of football, where for example the person with a previously injured leg has that leg planted and another player puts a shoulder pad into the lateral side of the leg.
Applicants are aware of only two prior art protective devices directed to this specific problem, and neither of these devices has proven sufficiently satisfactory to come into widespread use. These two prior art devices are made in accordance with disclosures in U.S. Pat. No. 4,249,524 to Anderson and U.S. Pat. No. 3,528,412 to McDavid. The Anderson device consists of arms adapted to be attached to the lateral side of the thigh and calf, respectively, either by tape or neoprene wrap held with Velcro. The proximal or near ends of the arms are pivotally connected to opposite ends of a rigid metal bridge, the purpose of the device being to receive lateral forces at the bridge instead of such forces being applied directly to the knee, and to distribute such lateral forces to the femur and tibia. The Anderson device is intended to be used by football players, but it has problems such that football players in fast running positions, such as running backs, ends and the like, will not wear it. One problem is that the Anderson device has single-overlap pivots which must be fairly tight for stability, resulting in too much friction during running and hence impairment of full running freedom. Another problem with the Anderson device is that lateral force against the bridge tends to be applied to the leg primarily directly under the regions of the pivots, which is still fairly well localized at regions close to the knee, and not distributed well along the lengths of the arms to which the bridge is pivoted. A further problem with the Anderson device is that although it is biaxially pivotal, the movements at the two pivots are completely independent of each other, so that just one or just the other of the pivotal connections may move, which may cause a slippage. Also, the pivots are too far apart to simulate the hinging action of the human knee.
The device of the McDavid patent is essentially the same as the Anderson device except it has only a single single-overlap pivot located generally proximate the knee. The McDavid device has the same two principal problems as the Anderson device, namely, the single-overlap pivot needs to be fairly tight for stability, resulting in an undesirably large amount of friction during running, and lateral forces against the raised pivot tend to be applied to the leg at localized regions close to the knee and not distributed well along the lengths of the pivoted arms strapped to the thigh and calf.
Applicants are aware of a number of other prior patents directed to knee braces for protecting or supporting or limiting the motion of injured knees, but are not aware of any devices other than the Anderson and McDavid devices manufactured for the purpose of protecting the knee from lateral forces or impacts. Two of these patents, Erichsen U.S. Pat. No. 4,381,768 and Lerman U.S. Pat. No. 4,372,298 are relevant to the present invention because of biaxial, geared hinge structures similar to the geared hinge structure employed in applicants' invention. Stops are provided on the Lerman gears to limit the travel in both directions. However, neither the Erichsen or Lerman devices would be usable to absorb and redistribute lateral forces or impacts. Thus, in both of these patents, the hinged arms are described as being rigid. In Erichsen, the hinge appears to be right against the side of the knee so that lateral forces or impacts would be directly transmitted to the knee, and in Lerman, pads are attached to the hinges on opposite sides of the knee, so that lateral forces or impacts against the hinge on the lateral side of the knee would be transmitted through the respective pad directly to the knee.
Cummins U.S. Pat. No. 4,245,629 states that one of the purposes of the disclosed device is for absorbing and spreading an external blow, and Cummins is also of interest because it discloses a biaxial-type hinge structure, although it is not geared. This is a double overlap-type hinge with three tongues, described as being rigid, extending from each side of the hinge and independently pivoted in the hinge. The Cummins device does not appear to space the hinge structure from the knee, and it appears that lateral forces or impacts against the hinge would be applied directly to the knee joint or through the rigid tongues to localized regions of the leg very close to the knee.
McClure, Jr. U.S. Pat. No. 3,350,719 discloses substantially flat upper and lower brace bars that appear to be rigid, connected at a biaxial hinge. Lateral forces or impacts would either be applied through the hinge directly to the knee or through the brace bars to localized regions close to the knee.
Peckham U.S. Pat. No. 3,194,233 discloses lateral and medial leaf-type springs which bow outwardly. There is no means disclosed in this Peckham patent for spreading force to the femur and tibia at substantial spacings from the knee, and sponge pads are compressed against opposite sides of the knee joint by knee-encircling members which would cause impacts to be transmitted directly proximate the knee joint. Another Peckham U.S. Pat. No. 2,467,907 also discloses bowed springs, but so arranged that impacts would be applied directly to the knee joint. Schulman U.S. Pat. No. 3,074,400 also discloses springs in a kneecap brace, but these are not hingedly connected.
Patents such as Whitehead U.S. Pat. No. 3,898,697 and Buring U.S. Pat. No. 4,409,689 are exemplary of a number of patents which disclose shell-like forms fitting over portions of the upper and lower leg adjacent to the knee.
Applicants are aware of no prior art patent or device wherein leaf spring members are hinged together by means of a hinge substantially spaced laterally from the knee joint, and respectively rigidly connected to generally rigid thigh and shin shells at locations remote from the knee joint so as to absorb forces and impacts directed toward the lateral side of the knee and distribute such forces and impacts in a cushioned manner at locations spaced substantially from the knee and in regions of strong bones of the leg.
A problem with any knee brace is that it has a tendency to slide or migrate downwardly on the leg. This causes the hinge structure of the brace to shift out of registry with the knee joint, increasing the amount of effort required to bend the leg at the knee, and thereby generally defeating the purpose of the brace. Once downward migration commences, the strap means above the knee that is usually engaged about the thigh will rapidly loosen because of the downward and inward taper of the thigh, further impairing the utility of the device. Because of the large amount of motion at the knee joint, this downward migration problem is, in general, more serious for athletic knee protectors than for knee braces used in a less active or more sedentary way.
While a variety of calf attachment straps is provided on most knee braces as seen in the various prior art patents cited above, prior to the present invention none has been suitable for positively preventing downward migration of a knee brace, and particularly the downward migration of an athletic knee protector for protecting the knee against lateral blows. The prior art calf attachment straps have been, in general, spaced too far down below the knee joint to gain a satisfactory purchase against the initial and greatest flare of the calf immediately below the knee joint so as to provide a positive lock against downward migration. The devices disclosed in the Anderson U.S. Pat. No. 4,249,524 and McDavid U.S. Pat. No. 3,528,412 are athletic knee protector devices for protecting the knee from lateral blows, but they fall into the general category of knee braces which have calf attachment straps that are too low on the calf to prevent downward migration of the devices on the leg. The Erichsen U.S. Pat. No. 4,381,768 referred to above has a pair of straps 40 and 50 attached to the device close to the knee joint, but these straps cross over behind the knee so as to preclude engagement against the outwardly and downwardly flaring part of the calf. The knee brace disclosed in the Lerman U.S. Pat. No. 4,372,298 referred to above has a pair of straps 96 and 98 close to the knee joint, but these hold condyle pads in contact with the sides of the knee so that these straps are at the knee joint and could not engage against the flaring part of the calf. These straps 96 and 98 are elastic, which would further preclude their use as a positive stop against downward migration of the brace.